dtoa
This crate provides fast functions for printing floating-point primitives to an
io::Write
. The implementation is a straightforward Rust port of Milo Yip's
C++ implementation dtoa.h. The original C++ code of each function is included
in comments.
See also itoa
for printing integer primitives.
Version requirement: rustc 1.0+
[dependencies]
dtoa = "0.4"
Performance (lower is better)
Examples
use std::io;
fn main() -> io::Result<()> {
// Write to a vector or other io::Write.
let mut buf = Vec::new();
dtoa::write(&mut buf, 2.71828f64)?;
println!("{:?}", buf);
// Write to a stack buffer.
let mut bytes = [b'\0'; 20];
let n = dtoa::write(&mut bytes[..], 2.71828f64)?;
println!("{:?}", &bytes[..n]);
Ok(())
}
The function signature is:
fn write<W: io::Write, V: dtoa::Floating>(writer: W, value: V) -> io::Result<()>;
where dtoa::Floating
is implemented for f32 and f64. The return value gives
the number of bytes written.